3.3

Capsules and slime layers

Capsule- distinct, tightly bound layer

Slime Layer- loose, irregular coating

Function: protection and attachment

Biofilms

• Formed when bacteria produce large amounts of glycocalyx

• Dense matrix of polysaccharide, proteins, and nucleic acids

Flagella Types

• Peritrichous – flagella all around

• Monotrichous – single, polar flagellum

3 parts of bacterial flagellum

• Basal body: anchors to cell wall and cytoplasmic membrane

• Hook: flexible joint that connects the basal body to the filament…allows rotation

• Filament: made up of flagellin subunits

Chemotaxis

nutrients attract / toxins may repel

Aerotaxis

toward/away from O2

Magnetotaxis

Align with Earth’s magnetic field lines; vertical component – can move downward toward low O2 environment

Thermotaxis

temperature

Phototaxis

light

Fimbriae

• Protein-based; extend from cell

• found in gram - and gram +

• function in surface attachment

Pili

• Protein-based; extend from cell

• Shorter than flagella and longer that fimbriae

• mainly gram - bacteria

• function in attachment and motility

Sex Pilus

• specialized pili that function in attachment for gene transfer